Apparatus and process for improving separation of clarified liquid from a slurry by subdividing the slurry at the separation interface into a plurality of shallow streams



Aug. 12, 1947. w, GREEN 2,425,371

APPARATUS AND PROCESS FOR IMPROVING SEPARATION OF CLARIFIED LIQUID FROM A SLURRY BY SUBDIVIDING THE SLURRY AT THE SEPARATION INTERFACE INTO A PLURALITY OF SHALLOW STREAMS Filed Jan. 7, 1943 3 Sheets-Sheet l uwmox W Gr en, A

W. H. ROCESS FOR IMPROV FROM A SLURRY BY SUBDIVIDING THE SLURRY AT THE SEPARATION Aug. 12, i947. GREEN. 2,425,371

APPARATUS AND P ING SEPARATION OF CLARIFIED LIQUID INTERFACE INTO A PLURALITY OF SHALLOW STREAMS Filed Jan. 1943 3 Sheets-Sheet 2 Aug. 12, 1947. w, GREEN 2,425,371

APPARATUS AND PROCESS FOR IMPROVING SEPARATION OF CLARIFIED-LIQUID FROM A SLURRY BY SUBDIVIDING THE .SLURRY AT THE SEPARATION.

INTERFACE INTO A PLURALITY OF SHALLOW STREAMS Filed Jan. 7, 1945 3 Sheets-Sheet 3 INVENTOR.

83 32 rrazzerflarem/ which clarified Patented Aug. 12, 1947 FlCE- APPARATUS AND PROCESS FOR nuraovmo SEPARATION OF CLARIFIED LIQUID FROM A SLURRY BY SUBDIVIDING THE SLURRY AT THE SEPARATION INTERFACE INTO A PLURALITY OF SHALLOW STREAMS WalterH. Green, v Incorporated,

Delaware Batavia, Ill., assignor to Infilco Chicago, 111., a corporation of Application January 7, 1943, Serial No. 411,634

18 Claims. 01. zit-1.6)

, This invention relates to an improved method and apparatus for the treatment of aqueous liquids, such as the softening or clarification of water.

One of the principal objects of the present invention is an improved process and apparatus for the softening of a hard, or the clarification of a turbid, water.

Another object of thepresent invention is an improvement upon the slurry process in the treatment of water.

A further object of the invention is to provide means for separating clarified water from the upper surface of the slurry pool, and for rapid removal from such surface of solids accumulating thereat due to the separation of clarifiedv water from the slurry.

Another object of the invention is to provide an improved process and apparatus for the purification of water by a method wherein the water is treated with a cipitate impurities therefrom and thesubsequent separation of said precipitate and water.

A still further object of the invention is the provision of an improved process and apparatus forthe purification of water by chemical reaction in'thepresence of a large amount of slurry containing particles separated and accumulated from previously treated water while in a state of suspension, the reaction' being controlled to produce large and heavy particles of the precipitate from water can rapidly be separated.

These and other objects of the invention will be apparent which follow.

In the field of water treatment, it has longbeen known to treat water with a chemical reagent. such as lime, in order to precipitate impurities from the water. For many years it was thought necessary to gently mix the water and reagent for a prolonged period in what is commonly called a flocculation step and then subject the treated water to a prolonged sedimentation step in which the water is held in a quiescent condition for a period of several hours, during which time the fine precipitate formed by the reaction of water and chemicals would settle out. This type of process required large tanks to accomplish the necessarily long holding time, as the precipitate formed by the reaction was very fine and required a long time to deposit from "the water and also it was necessary to hold the water several hours to arrive at a sufiicient state of chemical and physical stabilization. The mixing of chemical the slurry treatment of water, an improved precipitating reagent to pre-' from the description and claims' and water in the flocculation step necessarily was gentle as it was found that turbulent mixing destroyed the particles so formed while gentle mixing permitted their flocculation into larger particles which would settle more rapidly.

A more recent development in the field of water treatment has been that wherein the treatment is carried out in, and in part by, a suspension containingparticles separated and accumulated from previously treated water to form a slurry. This slurry type treatment has within the last few years very largely displaced the old flocculation and sedimentation processes so far as new installations are concerned, and has been the subject of various patents such as those to Green Reissue No. "22,194, Spaulding 2,021,672 and Hughes 2,245,587. In the Green and Hughes patents particularly the water to be treated and the treating reagent are turbulently mixed in and witha slurry containing a large amount of solids separated and accumulated while in a suspended condition from a relatively large-amount of previously treated water. The invention of the present application may to an extent be considered as directed to improvement on the apparatus of the above mentioned Green and Spaulding patents. It has been found that insuch slurry treatments, the newly formed deposit by accretion upon the particles already formed, particularly if there is sufllcient movement of the water and solids forming theslurry to provide for a continuous flushing of the film of pure water which tends to form around the particles when the'nascent precipitate has been removed therefrom, which film hinders contact of such particles with water containing nascent precipitate. The slurry treatment is quitenew and presents many problems and difllculties not found in the prior art of flocculation and sedimentation. One of the most important problems arising in slurrytreatmentlies in the separation of clarified water from the slurry at the upper surface of the body of slurry. The solids formed in such a slurry treatment are so conditioned as to form relatively tough and dense particles from which clarified water may readily escape. However, with the escape of clarified water there is a correspondingly rapid abandonment and accumulation of solids at the slurry surface, which I i have found tends to interfere with the process.

My invention relates to an improved method and precipitate tends to i present new slurry be displaced. Thus, one of the'principal objects of my invention is to provide amethod and apparatus whereby clarified water and solids maybe rapidly and efficiently removed from the slurry at the upper surface of. the body of slurry used in the treatment so that the separation of water from slurry can proceed rapidly and efficiently.

As a result ofobservation and consideration of such apparatus and processes as those of Green and of Spaulding referred to, and of. other ob,- servations and tests, I have found that while favorable conditions have been provided for mixing and reacting the water and'precipitating reagent'in and with the slurry, the conditions provided for clarification can be greatly improved, so that to an extent what I'now propose is of from which clear water can of the body. of" slurry where-they otherwise tend to accumulate and interfere with therapid escapeof clear water. Such deposited solids will slide down the plate and be resuspended in thebody of slurry below, but they are removed from that I portion of the process where they are not needed.- l Preferably the plates are so placed as to'provide streams of the order of about '6 to 12 inches] thick and of a vertical height about two to four timesthe thickness of the stream. The distance between the plates and their vertical width is not closely critical and can be increased or decreased the nature of improvement 1011 such apparatus 1 and processes. I have discovered that by changing theconditionsat and Just below theslurry surface at, or from, which the clear water escapes substantial advantage can be obtained in the way of a very considerable increasein the rate of escape of clear water. I have found. that solids abandoned at, or adiacent, the slurry surface, or accumulating there, interfere with the approach and escape of water there and that if these solids are removed the rate of escape may be-substantially increased; In my copending application, Serial No. 471,635, died January r, 1943, 1 have proposed the washing away of these abandoned solids by a flow of, or in, the slurry adjacent the escape surface. That method is very effective but I have found that similar results may be had if instead of carrying the solids away in-a circulation of slurry I provide means by which they may deposit on asolid surface without having to move far to reach that surface. In this way theinter ference effect is minimized. When I speak ofin-- terference efl'ect I am not referring to a simple obstacle effect but of something more complex,

involving factors, the relations of which I do not yet fully understand, such asfor instance, the direction of approach of liquid and solids to the escape surface; Thus I have found that the face.

according to the-conditions of treatment, but

under ordinary circumstances little is gained by putting them closer for the conditions'that exist in the confined sloping space between them are not as simple as in an open space. As the plates,

are spaced farther apart the advantages gained decrease but not necessarily proportionately, and

may still be very substantial, and particularly so with some precipitates; However, it has. been 7 found that as th distance between the plates is increased, the height should be increased pro.- portionately as the .thicker the stream of slurry the longer it takes the solids separated from water at the surfaceto be'removedfrom slurry at the slurry face. I prefer to use plates sloping at an angle of approximately-or a little more.

as that is an angle. which will permit the solids depositing on the plates to slide down intothe body of slurry'below. While plates sloping at a steeper angle can be used, it has been found that as the plates slope more" steeply they afford less benefit, thereby increasing the numberrequired and the costof the apparatus. The vertical height of the plates should, as

noted above, be substantiall more than their, horizontal spacing. They are desirably at leastof such height that the solids abandoned between them can descend vertically, to a plate sur I Conditions should be established so that the slurry surface can be maintained between greatest degree of interference generally occurs" when the liquid flow is vertically to theescape surface in, or. with, the slurry in an-open area or chamber and least when the liquid or slurry is delivered substantially horiz'onally to, or lust below, the escape surface as referred to in the above copending application. I now find that while great benefit, can be had if theslurry rising from below passes between, or over, the-deposit surfaces, additional advantage can behad it instead there is a lateral delivery or flow between,-

or over, these surfaces. i

I have found that the separation of water and solids from the slurry can be most readily secured by dividingthe slurry in the upp r portion of a body of slurry into a plurality of thin streams by relatively narrow sloping plates intersecting the upper surface of.the bodyof slurry. The direc-' tion of flow of these thin streams, as they rise to the slurry surface, has a horizontal component greater than its vertical, for flow is preferably lengthwise along the blades as well as across them, and this type of flow, for the sak of brev-' ity, will sometimes be spoken of as diagonally rising." -When the upper portion of the body of slurry is so divided into the thin streams above mentioned, the solids left .behinduponthe escape of clear water will readily deposit, without having to travel farrupon the sloping plates and thereby be quickly removed from that portion them. When they are fed from below, the slurry surfacemay vary somewhat in elevation,' .and this may make it desirable to make them vertically wider, but extreme width, is rather to be avoided because then deposited solids stay longer on them and must flow down a longer slope,- I which seems to be undesirable. 'When the slurry I is fed in from the side or edge the slurrylevel The invention will'be more readily hereof and in which like reference characters designate similar elements. j

Figure 1 discloses a Plan view,'with motor and supporting structure removed, of one embodie 'ment of my invention.

Figure 2' discloses a horizontal cross-sectional view/of the apparatusshown in Figure 1.

Figure 313 a plan view, with motor and sup; porting structure removed, of a second embodlment of my'invention. f l r Figure 4' is -a vertical cross-sectional view of the apparatus shown in Figure 3 along the ver-: tical planes designated by the lines 4-4 of Flgure 3.

Figure 5 is a plan view of another embodiment. of my invention, shown as appliedparticularly to the'type of structure shown inmy patent Re.

Figure 6 islaverticai cross-sectional view. of the apparatus shown in Figure 5.

Referring to Figures 1 and 2, it will be, seen that theapparatus of the present invention is enclosed in a tank"! which may be oi any size or shape but which may include a vertical wall H, a hopper bottom l2, and a floor l3. The

' upper edge or the vertical wall I I is provided with ing impeller 25 mounted upon a shaft 26 which is journaled in suitable bearings, such as 21, and driven by a motor-reducer 28. The impeller 25 may be placed in various levels of the tank, in Figure 2 it is shown as being at an intermediate level while in Figure 4 it is shown as being adjacent the floor of the tank. The location will depend to some extent upon the direction oi. fiow, which in Figure 2 is downwardly from the impeller and in Figure 4 is upwardly therefrom. If desired, agitating bars 29 may also be mounted upon the shaft 25 in order to secure a more thorough and turbulent mixing of liquid thereby. The motor reducer 28 is supported above the tank by beam 39.

Surrounding the impeller 25 I cylinder 35 extending upwardly from a level,'such as 36, adjacent the floor of the tank and either extending above the liquid level in the tank, as

:steeply sloping settling plates, which in Figures 1 and 2 are shown as longitudinal plates 39extendin radially'from the partition 35 to the wall ll of the tank. Preferably the plates will have a slope of 45, or a little more so'that solids depositing thereon will fiow orslide by gravity downwardly and oil the lower. edge- .49. The settling plates 39 must have a vertical extension at least tothe upper edge of the communication 38, and should extend some distance above, say' a distance about the same as the spacing of the plates 39 at the periphery of the cylinder 35. Preferably the top edge 4| will overlie the lower edge 40 of the adjoining plate in order to prevent direct passage of liquid from the lower portion of the tank into the quiescent upper portion. The plates 39 can be placed at any desired distance apart, and can have any desired vertical height, but I hav found that plates about 4 to 12 inches apart and with a vertical height of about three times the distance between plates are very efiicient. Obviously, where the plates are placed radially as herein described, the disis a partition or,

tance between the plates will vary as the distance from the center increases, which is permissible so long as the vertical height of the plates at the periphery is sufficient to permit; the top'edge 4| of one settling plate to well overlap the lower edge ll! of the adjacent one. In larger tanks it may be advantageous or necessary to put plates extending part way in from the periphery inter mediate the others, as indicated at 45.

Water to be treated and a chemical reagent v cient amount.

may be introducedv in v any desired manner. In

the embodiment shown in Figures .1 and 2, in

which the flow from the impeller 25 is downwardly through the cylindrical partition 95, I may introduce both into the upper portion of the cylinder 35. In this embodiment, water is shown introduced through inlet conduit 42 and chemical reagent through chemical feed line 43, both of which are shown as discharging into theopen top 0! cylinder 35. t

It will be seen that the structureherein described divides the tank l0 into a a mixing zone 59defined by the cylindrical partition 35; an up,- per quiescent or clarified liquid zone 5| adjacent the upper portion of the tank; a clarification zone 52 within-the upper and lower limits of the settling plates 39,- and a flow space 53 in the lower portion of the tank and outside of themixing zone. The mixing zone 50 and the flow space 53 together form what might be called a reaction space in the bottom of the tank llasordin'arily the reaction between water and reagent may take place in both themixing zone and the flow space. This reaction space is functionally separated from the clarified liquid zone 5l by the sloping plates 39 or by the clarification zone 52 established by such plates. 1 i

The operation of theapparatus will be obvious. Assuming that the apparatus has been in operation and a body of slurry has been accumulated, which will extend from the floor l3 to a level intermediate the top and bottom of the settling plates 39, water and reagents are supplied through their respective inlet conduits l2 and 43 into the open upper end, of the mixing zone 50. It will be understood that water and reagent may be sup and showmor', as discharging as separate streams in different parts of. the tank such as supplying one in the flow space 53 and the other inthe mixing space 50. Rotation of the impeller'25 causes a downward fiowoi considerable volume through the mixing zone 58 and out the lower open end 36 thereof, where it is deflected outwartily and upwardly. i- Th'e horizontally expanding'garea of the lowergportion of the tank will that the rotation of the slurry in space 53 will be toward the back or lower side ofplates39 so as not to be caught and deflected upwardly between the plates. The vertical rise of water in the lower portion of the tank is then dividedbythe sloping plates "into thin, diagonally rising, streams as it passes between the plates. The slurry level, which ,will be substantially horizontal entirely across the area ofthe tank, must be maintained at a point intermediate the lower edgetband upper edge M of the settling plates 39. This circulation tends to raise the slurry to a level about that oi the top of opening 38 and unless the circulation velocity is too great it will not go higher unless solids are not discharged to waste in In the clarification zone, estate lished by the sloping settling plates, clarified water can escapefrom the slurry and thc soiids thereby left behind are rapidly removed from depositing upon the sloping plates. The l are thus removed from that portion oi the le'the rather vigorous flow issuing from the I slurry in which th'ey usually tend to accumulate and in which such an accumulation tends to bej come detrimental. Such solids quickly flow or I slide down the plates and are dispersed and re- 1 suspended in the slurry therebelow.

Preferably the impeller 25 will be of such size i and rotated at such speeds as tocause a flow of liquid of about twice the throughput of water or 1 flow without being deposited ontheplates. Ex-

1 cess solids can be withdrawn from the body of j slurry in the lower part or the'tank It) by any suitable means such as through the drain I1, as

1 shown in Figure 2. or throughthe sludge concentrator 60, shown in Figure 4;

It. is believed tobe obvious that the direction 1 of flow through the mixing zone 50 can be re- 1 versed so that the flow would be upwardly therein and thence horizontally adjacent the sloping ;plates 39,' and thence downwardly in the flow space 53 for recirculation. In this event the water and chemicals would preferably be introduced in the fiow space 53 or in the. lower part of the mixing zone 50 so as to provide a suflicient time for complete reaction between water and reagent and slurry before its discharge outwardly through communication 38. I

Inmanyrespectsthe apparatussh'own in Figures 3 and 4 is very similar to that shown in Figures 1 and 2. The general structure of the tank and the impeller and its associated shaft are the same as in-Figures 1 and 2. However, in Figure 4 is shown :a solids concentrating chamber 60 formed by a wall of the tank and a partition 6| A sludge out- :let 62 leads from the lower portion of the concentrator chamber and preferably is provided with a valve 63 to control the removal-of solids from the apparatus.

be so constructed as to permit the outflow of liquid therefrom horizontally on each side. For example the flow members 69 may comprise a fioor plate 10, a cover plate H, and be confined within side walls 12. The side walls 12 are provided with a slot 13 or other suitable apertures through which liquid can pass horizontally into the space between the settling plates 14, which are concentrically arranged around the cylindrical partition 35. As in the apparatus described in Figures 1 and 2, it is desired that the upper edge 15 of one settling plate overlie the lower edge 16 of the adjacent plate. .It is also preferred that the plates be horizontally spaced a relatively short distance apart, such as 6 or Sjinches, and thatthe height of the plates be two to four times the horizontal distance between them.

Water to be treated and a chemical reagent can be introduced through raw water inlet 11 and chemical feed line 18 discharging into the fiow space 53 or other suitable place as indicated above.

The operation of the structure shown in Figures 13am 4 is essentially'the same as that shown 1 more, so that part of the considerable amount of slurry starting to pass vertically between the 1 plates will be drawn horizontally. into the comj munlcation 33 and thereby returned to the mixing zone 50 and some of the solids abandoned by the escaping water will be carried back. with the in Figures 1 and 2. .For purposes ofillustration I .it can be assumed that the flow is upwardly within the mixing zone 50. A volume of slurry is drawn by rotation of the impeller-"upwardly through the mixing zone 50, preferably inan amount at least about twice that of the throughput of the treated water. The slurry passes through the flow members 69 and a portion of it will pass horizontally through the'slots 13 into 7 the spaces between the concentric sloping bullies and will maintain such horizontal flow for some distance. Clear water will escape from then!)- per surface of the slurry, which is preferably, maintained within the limits of the'upper edge 15 and the lower edge 16' of the settling plates 14, andpart of the solids thereby left behind will quickly sediment upon the slopingplates ll as a thin sludgethat will quickly flow or slide down the baflie plates and be resuspended in the body of slurry below. In this fashion the solids which ordinarily accumulate at the surface of the slurry are temporarily removed from that locality and returned to the process.

some of the abandoned solids, picking up raw water and chemical on the, way and be recirculated through the mixing zone 50. Excess solids are removed to waste by means ofthe concen-" trator 60 and the sludge outlet 62. If desired the flow can be reversed through the mixing chamber, in which case the location of the water into the mixing zone and chemical inlets would be changed to discharge 50,;as shown in Figures 1 and 2.

The apparatus shown in Figures 5 and 6 illustrates my invention when applied to an apparatus of the type described in my patent, Re. No.

22,194. In such an apparatus the tank 85 can be of any desirable shape but, is shown for purposes of illustration as cylindrical and defined by vertical wall 86 and fiat bottom 81. Treated water is withdrawn over a weirl4 into a launder l5 and thence to'use through a conduit IS. A

sludge outlet ordrain 88, having a control valve 89, is shown leading from the lower part of tank ikxially aligned in the tank is an agitator 90 I which may comprise a shaft 9| journaled in suitable bearings, such as 92, and driven by a motorreducer 28. Mounted on theshaft ill are horizontal arms 93 upon which are carried suitable paddles 94. Preferablythe upper portion of the shaft 9| is encased in a cylindrical tube 95 to prevent agitation of the water in the clarified water zone 5 A plurality of substantially vertical baflles I are placed radially in the tank 85, above the' agitator paddles 94, in order to reduce, but preferrotational movemaintained by ro-,

ably not entirely destroy. the ment of liquid established and tation of the agitator 90. Superimposed upon the vertical baiiles I00 are a plurality of narrow sloping settling plates llll which may be concentric conical segments as shown in Figure 6, or radial baiile plates as arranged in Figures 1 and 2. If the settling plates are in radial position, the bailles I30 may be omitted. The vertical baflies I00 and a the superimposed settling plates llll functionally divide the tank into a lower reaction space and an upper clarified water space separated by the clarification space52 at the level of the settling plates. A solids separating chamber I02 may be placed within the tank preferably centrally located with its upper edge I03 preferably above the level of the lower edge I04 of the slop- A large portion of the slurry will return to the fiow space 53 carrying 9' ing bafile plates and below the upper edge in! thereof. A solids outlet I06 leads from the lower portion of the solids separator 12, and flow therethrough will preferably be controlled by some suitable valve, such as I01.

Water and chemical reagent can be introduced in any desired location, such as through water inlet H and chemical feed line III.

In operation of this type of apparatus a body of slurry'is maintained 'in the lower portion of the tank 85, extending to a level intermediate the top edge I and the bottom edgelM of the sloping sedimentation plates Water is introduced through inlet conduit H0, andia chemical reagent through chemical feed line H I, and the two are thoroughly mixed in and with the slurry in the bottom portion of the tank'by rotation of the agitator 90. After rising a suitable distance the rotational movement of the water is reduced by vertical baiileslIlO. The upward flow of water is then defiectedby the sloping plates Hll intoa plurality of narrow streams rising diagonally, whereby the-solids maybe read-' ily deposited upon the sloping plates I0! and flow as a thin sludge or slide down to be resuspended in the slurry below; Clarified water will rise from the clarification zone 52, and after rising through the clarified liquid zone 5|, will be withdrawn to use over weir l4. v

In structures of the kind shown herein, the depth of the clarified liquid zone can be substantially less than that heretoforerequired. Preferably water clarified in the clarification zone 52 will be allowed a short free rise through a clarifled liquid zone 5|. In the past such a clarified liquid zone was maintained for a depth of several feet below the weir M in order to permit the substantially complete separation of solid particles from the liquid. Such a depth is required 'as I have 'found that with astagnant condition of the slurry at the interface between the slurry tinuous and substantial separation of solids from the slurry adjacent the upper limits thereof, which solids are not removedfrom the process but lower portion of said tank and a clarified water -10 used for treating water, that is, one in which water and reagents are mixed and reactedin and with a slurry.

Obviously, there are many modifications of the invention herein described which will be obvious to those familiar with the art so that the figures and specification herein are to be considered for ,purposes of illustration rather than of limitation.

Iclaim:

1'. A slurry type. water treating apparatus wherein water and a precipitating reagent are mixed in a pool of slurry having a clearly defined 'uppersurface from which clear water escapes comprising a tank having a clarified'wate' outlet from its upper portion, a plurality; of steeply sloping settling plates extending horizontally across the cross-sectional area of said tank at an intermediate level therein vertically spaced below said clarified water outlet, said plates functionally separating said tank into a' reaction space in the space overlying saidreaction'space,"means for only temporarily removed from the area where they are most apt to cause di'ificulty, This provides for a constant return of solids from the interface between the slurry and clear water to the mixing space for reconditioning and growth.

When theplates are arranged as herein described as preferred forms, the depth of theclarified liquid zone can be much less than heretofore, as, due to the return of the slurry particles to the mixing zone, there is less tendency of the solid particles in the slurry to disintegrate and rise with of water being treated and a quantity of solids horizontal of about 45 or more;

supplying water and a reagent into the reaction space, a solids outlet at a level below said clarified water outlet, and'means to cause a horizontal flow r of slurry along said plates, said means including a mechanically driven liquid moving member in said reaction space, a partition structure surrounding said liquid moving member and extending from adjacent the bottom of said tank to adjacent the level of said settling plates, anda motor operatively joined to said liquid moving member.

2. Apparatus as described in claim 1 wherein the settling plates slope at an angle'from the 3. Apparatus as described in claiml wherein the horizontal distance between adjacent settling plates is less than the vertical height of said Plates, v

4. Apparatus as described in claim 1 wherein the settling plates are of suchwidth'an'cl so'positioned that the upper edge of one plate extends over the lower edge of an adjoining'plate. 5. In a slurrytype water treating apparatus that includes a tank, a partition structure in said tank forming therein anagitation space and a quiescent space having a zone of clarified water in an upper portion thereof, a treated water out let leading from the upper partof said quiescent in said agitationspace, and a solids outlet from said tank, the combination which comprises a plurality of sloping, horizontally extendingand laterally spaced plates extending across the cross-sectional area of said quiescent space, and a passageway affording communication between the agitation space and the spaces between'said plates,lsai'd passageway opening horizontally into said last mentioned spaces whereby slurry passes horizontally along said plates.

6. Water treating apparatus comprising'a tank, a mechanically driven stream projecting impeller in said tank, a partition structure surrounding said impeller and extending upwardly from adjacent the bottom to adjacent the top of said, tank, a lateral opening in said partition at an intermediate level therein, a plurality of horizontally spaced horizontally extending sloping plates in said tank, said plates covering the area between said partition structure and the periphery of said tank at the level of said opening,-means for with- 11 1 drawing treated water from the upper portion of said tank, means for'the delivery of water and a wjtreating reagent into the tank at a level below said plates, and a solids outlet fromsaid tank.

7. Apparatus as described'in claim 6 wherein the sloping plates are arrangedjconcentrically in a said tank.

8. Apparatus'as described in claim 6 wherein the sloping plates are arranged'radially in said I tank,

9. In ,water treating apparatus of the type 1 '1 wherein treatment is applied .to water in a slurry containing solids separated and accumulated from previously-treated wateran'd clarified water escapes from the upper surface of the slurry, said apparatus comprising a tank, an' opening through which water to be treated is supplied into the tank, means for delivering reagent to the water to be treated, an outlet for treated water adjacent the top of the tank, a solids discharge-outlet from the tank, a plurality of laterally spaced horizontally inclined sloping settling plates supported in g 7 said tank at a level below the treated water-out- 4 let, improved meansfor delivering slurry into the spacesbetween said plates, said means comprising rounding said impeller and cent the top thereof, a lateral opening in said partition structure at an intermediate-level in said tank, aplurality of sloping plates extending concentrically insaidtank around said partition at the level of saidopening a flow member extending horizontally from said opening in saidpartition toward the wall of said tank, lateral openings in said flow, member so-con 'structed and arranged asto provide communi;

cation between said fiow member and the. spaces between adjoining plates,'.an inlet for water to V be treated into the slurry holding space, an inlet for delivery of a treatin reagent to the water tobe treated, a solidsoutlet fromsaidtank, and an outlet for treated water fromthe upper portion of said tank, said; inlets being ,vertically' spaced below said outlet for treated water.

a partitionstructure extending vertically-in said" tank from adjacent the bottom thereof to adjacent the top thereof and enclosing'a flow space, an opening in the side of saidstructure at the level of and adjacent ends of said plates and power means for causing flow of slurry through said opening and said flow space.

10. A water treating apparatus of the type wherein treatment is applied to water in a slurry containing particles separated and accumulated from previously treated water and clarified water rises abruptly from the upper surface, of the slurry, comprising a tank, a wall structure in said tank dividing the same, into a, mixing space anda quiescent space, a clarified water outlet at the upper end of said quiescent space, a solids discharge opening from said tank, a shaft in said mixing space, a liquid impelling membenmounted on said shaft, a motor connected to. said shaft, an inlet for introducing water to betreat: 'ed into said mixing space, a conduit for. delivering reagent to the waterto be treated, afiplu rality of laterally spaced inclined'settling plates -mounted in and extending horizontally across .said quiescent space at an intermediaterlevel therein, and a passageway between said mixing spaceand said quiescent space belowthe level of the top of such settlingplates.

11. In water treating apparatus comprising a tank, said'tank havin inlet means for delivering water to be treated and a' treating reagent int the lower portion thereof and treated water discharge means adjacent the top thereof, an

' fined in a p and a treating reagent to? within said slurry holding space, and a power driven slurry moving member positioned withinv the said-slurry holding space, means for. conditioning the surface layer of slurry, t favor escape of clarified water therefrom, said means comprisin a series" of sloping, horizontally extending laterally spaced plates positioned in said tank atsuchan eleva;

tion as to penetrate the normal slurry surface during o eration, the width of saidplates being such'that the top and bottom edges of adjacent plates verlap, whereby the slurry adja I cent saidsur ace layer is subdivided and conality of relatively narrow sloplng flow passages,

, 14. A method of treating water, which corn; prises maintaining a body of'slur'ry accumulated V g from previously treated water, circulating slurry through a cyclicipath. which includes aflow fromathe lowerfportion of said body to adjacent the upper surfacethereof, passing tthe fiow of slurry adjacent the upper surface horizontally intc a pluralityuof narrow passageways,defined laterally by jsloping surfaces and open atr top and bottom, whereby solidsrmay benfdeposited upon such surfaces and slide'downwardly there-. on, returning: a'portion of such slurry downgdwardly into the lower portion of the .bodyof agitator for producing a'rotary motion of liquid in the lower portion of the tank and over substantially the whole area thereof, bafliemema bers located over said agitator and so arranged asto diminish said rotary .motion, and a solids separator having an inlet opening adjacent said baflle members, the combination with said ballle members of a plurality of sloping settling plates above said baflle members. 7

12. Water' treating apparatus of the. type wherein there is maintained a pool of slurry from the upper surface of which slurry clear water escapes comprising a tank, a lower porition of which forms, a slurryvholdin space and an upper portion of which is a clarified water space, a mechanically driven stream projecting impeller in said tank, a partition structure surslurry, mixing water to-be treated and treating" reagent in said circulating slurry separating clarified water fromsaid slurry in said passageways, withdrawing said clarified water from above said body of slurry, and withdrawing solidsfroin thesaidbodyofslurry. l 15. A method of treating water which come prises maintaining a bodyof slurry accumulated Y from previously treated water, mixing wateritof be treated and a treating reagent in :andwlth said slurry, separatingclarified water from the upper surface of saidslurry, withdrawing said clarified water from above said body of slurry and withdrawing exces solids from said body of slurry, characterized by the stepslof maintain ing a circulation in said body of slurry from the bottom to'th'e upper-surface of said slurry, thence, horizontally I and finally l returni g 1 to the lower 1 extending upwardly I from adjacent the. bottom of said tank to adJa-Q V portion of said body, dividing said horizontal flow into a plurality of shallow, thin and diagonally of clarified water, and withdrawing excess solids to waste from said slurry, characterized by the steps of applying energy to maintain a flow of water to and through said clear water escape.

suri'ace, subdividing said flow of water into a plurality of shallow streams whose direction of flow has a major horizontal component and underlying each stream with. a steeply sloping solids receiving surface, whereby escape of clear water from said clear water escape surface is promoted.

17. The process of treating water to efiect separation of the waterandsolid particles which comprises the steps of establishing a single vertical generally cylindrically and uniformly rising column of water undergoing treatment substantially free of obstructions which'restrict vertical flow, delivering water to be treated into the lower portion of said column, accumulating in said lower portion of the column solids from previously treated water to form a slurry, agitating the slurry in the lower portion of said column to produce a movement having a major rotational component to maintain in suspension substantially all solids therein, reducing the rotational movement of the slurry rising out of the zone of agitation to create a region of relative quiescence in the upper portion of said column, withdrawing solids to waste from the slurry rising in a portion of said region of relative quiescence and withdrawing treated water from said column above the level of solids withdrawal, deflecting the slurry rising out of the zone of agitation into the zone of relative quiescence in a direction that has a horizontal component greater than its vertical and dividing it into a plurality of shallow streams, defined laterally by sloping sur- 14 faces and open at top and bottom, whereby solids may be deposited upon such surfaces and slide downwardly thereon.

18. In a slurry type water treating process wherein water and r'eagent is mixed ln'and with -a body of slurry containing suspended solids accumulated from previously treated water and clarified water separates from the upper surface of said body of slurry, the steps of applying me- .chanical impelling energy to maintain a circulation in said body of slurry including a horizontal flow adjacent the slurry surface, dividing said horizontal flow into a plurality of shallow thin streams rising to said surface in a direction having a predominantly horizontal component, separating clarified water and solids in said streams of slurry, returning solids by gravity to a lower portion of said body of slurry, and withdrawing ,the clarified water from above said slurry surface.

'WALTER H. GREEN.

REFERENCES 5 CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 748,308 Reisert Dec. 29, 1903 2,245,583 Green June 17, 1941 2,296,437 Green Sept. 27, 1942 1,177,849 Kalb Apr. 4, 1916 1,030,366 Winters June 25, 1912 2,021,672 Spaulding Nov. 19, 1935 2,127,314 Spaulding Aug. 16, 1938 2,245,587 Hughes June 17, 1941 1,701,068 Flowers Feb. 5, 1929 1,009,857 Reisert Nov. 28, 1911 2,259,221 Darby et al Oct. 14, 1941 1,864,866 Snow June 28, 1932 495,313 Dervaux Apr. 11, 1893 2,179,246 Applebaum Nov; 7, 1939 2,314,977 Green Mar. 30, 1943 2,348,122 Green May 2, 1944 FOREIGN PATENTS Number Country Date 2,077 Great Britain Jan. 29, 1908 57,727 Germany July 30, 1889 

